1. The Field of the Invention
The present invention relates to a printed circuit board (PCB) having electronic components thereon, where the PCB is mounted into a connector. More particularly, the present invention relates to the shaping of one edge of a PCB for subsequent insertion of a substrate into a connector. In particular, the present invention relates to a printed circuit board cold-shaping tool that forms a bevel upon an insertion edge of the printed circuit board (PCB), where the bevel on the insertion edge is then inserted into an expansion slot of a computer system, and where the PCB is a memory module or any other kind of plug-in card.
2. The Relevant Technology
A printed circuit board, sometimes abbreviated PCB, is a thin plate on which chips and other electronic components are placed. Computers consist of one or more boards, often called cards or adapters, each of which has a plurality of electronic components thereon. A PCB is typically inserted into an expansion slot in order to place the electronic components thereon in electrical communication within the computer. The expansion slot is an opening in a computer where a printed circuit board can be inserted to add new capabilities to the computer. Nearly all personal computers, except for portable computers, contain expansion slots for adding more memory, graphics capabilities, and support for special devices. The boards inserted into the expansion slots are called expansion boards, expansion cards, cards, add-ins, and add-ons.
The PCB has electrical contacts that are in electrical communication with the electronic devices on the PCB. The PCB preferably has one or more bevels upon one edge in order to facilitate insertion thereof into an expansion slot for a digital computer, or other types of electronic devices. A smooth bevel is preferably formed along the edge of the card without disturbing the electrical contacts on the card. In a typical 72-pin card, the bevel has been conventionally formed by a cutting operation that removes material from the card. These cutting operations have typically been performed by machinery, such as with the Bevel Master(copyright) or Bevel Mate(copyright) each of which is distributed by Radoll Designs, Inc. located in the city of Thomasville, Ga., USA.
FIG. 1 is a cross-sectional elevation view of a prior art bevel device 10 that is used to cut a printed circuit board (PCB) 12 at an insertion edge 14 and at opposing parallel surfaces 30. PCB 12 is inserted into a slot 16 of a bevel jig 18. Bevel jig 18 may be supported by a base 20. As PCB 12 is advanced by forcing it through slot 16, a pair of knives 24 trim insertion edge 14 to form bevels. Insertion edge 14 is depicted as having a cross-sectional thickness that fits into and is slightly smaller than slot 16. During the trimming of insertion edge 14, a portion of PCB 12, called a trimming 26, falls away from PCB 12 and must be removed.
One of the problems that occurs in the prior art is that the presence of trimming 26 causes refuse and refuse management. Where a plurality of pins 28 are disposed along insertion edge 14 and have valuable metal such as gold that is cut away from PCB 12 as part of trimming 26, additional work must be carried out to recover and reuse the valuable metal in trimming 26.
Another problem that exists in the prior art is the fact that knives 24 are subject to losing a sharp edge and becoming dull due to on going use. As knives 24 begin to dull, successive PCBs will be beveled differently due to progressively varying degrees of sharpness of the cutting edge of knives 24. In other words, where printed circuit board 12 is the first to be trimmed by a brand new set of knives 24, a xe2x80x9ccleanxe2x80x9d cut may be performed, but the next printed circuit board will experience knives that are just slightly duller. Consequently, as the useful life of knives 24 nears their end, significantly different bevels on a PCB can be formed than when knives 24 are sharp.
Another problem occurs when one knife 24 may be sharper than another knife 24. An unevenness in sharpness during the beveling operation will cause a greater degree of friction on the duller knife 24. A difference or excessive friction on a knife 24 can cause PCB 12 to fragment instead of cleanly slicing insertion edge 14 of PCB 12. Also, the increased pressure against the duller blade of knife 24 will cause PCB 12 to bow or warp. Bowing or warping will in turn cause a greater volume of trimming 26 to be removed from either of surfaces 30 and/or insertion edge 30. Alternatively, if both occurrences of knives 24 are dull, the entire printed circuit board may be destroyed due to both uneven cutting, excessive friction, fragmentation, warping, or bowing. Still further, too large or too small of a volume of trimming 26 may be removed from one of opposite surfaces 30 of PCB 12. Consequently, an uneven formation of bevels may cause PCB 12 to be inserted into an expansion slot without proper registration in the slot. This improper registration can cause electrical communication between the expansion slot and the electric contacts on PCB 12 to be established on only one side of PCB 12.
Another problem that occurs due to the cutting nature of the prior art is, where the material of the pins 28 is scraped instead of cut by knives 24, the scraping causes the material of pins 28 to pull away from the surface 30. Where the material of pins 28 is harder than the material of PCB 12, or where the material of pins 28 is not efficiently bonded to the surface 30 of PCB 12, the material of pins 28 will be scraped away after a manner that causes it to delaminate from surface 30 of PCB 12. Consequently, the effect will be inadequate electrical contact when PCB 12 is inserted into an expansion slot.
Along the length of insertion edge 14 (the length is pictured as being perpendicular to the plane of the Figure), PCB 12 may have a varying cross-sectional thickness as PCB 12 is presented against knives 24. The varying cross-sectional thickness may also cause the cutting operation to be nonuniform. Where the cross-sectional thickness is too thin, cutting may not occur. Where the cross-sectional thickness is too wide, cutting may become irregular or improbable because PCB 12 may be forced out of slot 16.
What is needed in the art is a tool, and a method of using the same, that forms beveled edges in a printed circuit board while overcoming the problems of the prior art. Such a tool, and a method of its use, is disclosed and claimed herein.
The present invention relates to a printed circuit board (PCB) edge shaping tool, and method of its use. The inventive tool and its method of use overcomes the problems of the prior art associated with cutting and grinding to shape a PCB. The PCB has an insertion edge that extends between opposing parallel surfaces of the PCB. The PCB also has a bottom edge that is opposite of and parallel to the insertion edge. The inventive tool is used to form a bevel on the PCB without removing material from the PCB. The bevel formed by the inventive method of using the inventive tool extends between the insertion edge and each of the opposing parallel surfaces of the PCB.
The inventive tool includes a support surface for supporting the bottom edge of the PCB, and also includes a device for moving a shaping tool to form a bevel on the PCB without removing material from the PCB. The bevel is formed while the support surface supports the bottom edge of the PCB and while the shaping tool makes contact with both the insertion edge of the PCB and the opposing parallel surfaces of the PCB.
The printed circuit board can be a memory module or for any other kind of plug-in card such as a modem card, a video card, or an audio card. The inventive method using compressive forces to form bevels upon an edge of a printed circuit board without removing material from the printed circuit board (PCB). Prior to the beveling operation of the present invention, the edge of the PCB has a first shape that preferably is rectangular is cross section. The first shape is transformed into a second shape, which is preferably beveled, by the inventive method. Once the bevels are formed, the bevels aide in the insertion and registration of the printed circuit board into an expansion slot of a computer chassis.
In one embodiment of the present invention, a rolling cold-shaping tool rolls along an edge of a printed circuit board in order to form preferred bevel shapes. The rolling cold-shaping tool can be a single bevel wheel or a collection of in-parallel bevel wheels that may perform the cold-shaping function upon an array of printed circuit boards that may be set in a tray or other collective container. The shape of the edge of a PCB is transformed into the beveled shaped by the shaped, bevel wheel. The bevel wheel has a bilaterally symmetrical angled channel shape into which the edge of the PCB is inserted. Compressive stresses directed at the edge of the PCB accomplish the formation of the bevel shape without removing material from the PCB.
The present invention also relates to a cold roll bevel system. The cold roll bevel system comprises a PCB insert assembly that comprises two parallel, opposed, spaced apart, slotted structures disposed against a plate. The plate may be varied in length to accommodate different length PCBs. An edge of the PCB is inserted into the PCB insert assembly and is then compressed in a compressive tool such as a shaped wheel, a channel, or an articulating press. The compression forms one or more bevels in the edge of the PCB without removing material from the PCB. Where the compressive tool is a wheel, the wheel is driven along the edge of the PCB into which the one or more bevels are to formed. The present invention may be carried out by having an operator or a machine place a memory module or another PCB-mounted card into the PCB insert assembly. Where the length of the PCB may vary, the plate of the PCB insert assembly may be varied.
Under certain conditions, a plurality of memory modules may be processed to form bevels on an edge of the respective PCB according to the present invention. In particular, a plurality of parallel occurrences of a bevel wheel may be mounted upon a bevel wheel carriage and a corresponding plurality of memory module inserts may be disposed beneath the bevel wheel carriage. Under these circumstances, each occurrence of a bevel wheel may have a separate sensor in order to apply a preferred even pressure force upon each occurrence of the bevel edge.
In another embodiment of the present invention, formation of the bevel may be carried out by inserting the insertion edge of the PCB into a shaped channel. The insertion edge is then forcibly moved through the channel such that the insertion edge assumes the shape of the shaped channel without removing material from the PCB. As such, the insertion edge of the PCB will have a preferred bevel height and bevel angle. The shape of the channel in the present embodiment may be substantially the same, when viewed in cross section, as the shape of the bilaterally symmetrical channel of the shaped wheel of the previous embodiment.
In yet another embodiment of the present invention, the bevel may be formed by compression forces brought to bear upon the insertion edge of a PCB using the articulation of a press. The pressure upon the insertion edge forms bevels having both a bevel height and a bevel angle without removing material from the PCB. The cross-sectional view of such an articulating press in the present embodiment would be substantially the same when in a closed position of such a press as that of the bilaterally symmetrical channel of the shaped wheel of the previously described embodiment.
These and other features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.